The present invention relates to a thermal sensitivity calculating apparatus for calculating thermal sensitivity, e.g., an equivalent temperature (Teq), felt by a human body, and a predicted mean thermal sensitivity calculating apparatus for calculating a PMV (Predicted Mean Vote) value as predicted mean thermal sensitivity representing the degree of comfort in an indoor environment.
The equivalent temperature Teq is used as an evaluation index of a thermal environment felt by a human body, i.e., thermal sensitivity.
As the first method of obtaining this equivalent temperature Teq, a method is proposed, in which an equivalent temperature Teq.sup.* substantially equal to the equivalent temperature Teq of the human body is obtained by measuring a radiant temperature Tr, an air temperature Ta, and an air velocity Vair by using different sensors, and performing predetermined arithmetic processing of the measured values. This method requires complicated arithmetic processing, and the processing time is undesirably prolonged.
Under the circumstances, as the second method of obtaining the equivalent temperature Teq, a method is proposed, in which a heater is incorporated in a module main body, and the amount of power to be supplied to the heater is controlled to maintain a temperature (sensor temperature) T.sub.cr of the module main body at a constant value (e.g., 36.5.degree. C.). According to this method, the equivalent temperature Teq.sup.* can be calculated by measuring the amount of power to be supplied to the heater and performing predetermined arithmetic processing of the measured value.
In a conventional method, as a formula for calculating predicted mean thermal sensitivity PMV representing the degree of comfort in an indoor environment, the PMV equation defined by ISO 7730, i.e., the following equation (1), has been employed: ##EQU1## Tcl=clothing surface temperature Tsk=skin temperature
Pa=RH-Pa.sup.* PA0 RH=humidity PA0 Pa.sup.* =saturated water vapor pressure PA0 M=activity amount PA0 W'=work amount PA0 Ta=air temperature PA0 Tr=radiant temperature PA0 Icl=clothing thermal resistance PA0 Vair=air velocity PA0 fcl=factor
According to this method, the predicted mean thermal sensitivity PMV can be automatically calculated by measuring the respective parameters and substituting the measurements into equation (1).
In practice, however, it is difficult to measure all the parameters in a room of a building. Moreover, the above PMV equation itself is complicated.
Under the circumstances, the present applicant has proposed a method of obtaining a predicted mean sensitivity PMV.sup.*, as a value coinciding with the predicted mean sensitivity PMV with high accuracy, by using the above-mentioned equivalent temperature Teq.sup.* and simple formulae.
In the above-described second method of obtaining the equivalent temperature Teq, however, since an environment measuring section constituted by the module main body and the heater is much smaller than a human body, the air current sensitivity of the measuring section is much larger than that of the human body.
This difference in air current sensitivity indicates that the equivalent temperature Teq can be properly measured within a low air velocity region in which the air velocity Vair is about 0.1 m/s, whereas the deviation of the equivalent temperature Teq.sup.* from the equivalent temperature Teq is increased in an air velocity region in which the air velocity Vair is higher than 0.1 m/s, and accurate measurement cannot be performed. That is, even with a slight increase in the air velocity Vair, the equivalent temperature Teq.sup.* becomes much smaller than the equivalent temperature Teq because of the high air current sensitivity.
According to the second method described above, therefore, there is a critical drawback that accurate measurement cannot be performed when the air velocity Vair is high, in spite of the advantage that the radiant temperature Tr, the air temperature Ta, and the air velocity Vair can be integrally measured, i.e., the advantage that the arithmetic processing can be simplified.
The difference between the equivalent temperature Teq and the equivalent temperature Teq.sup.* affects arithmetic processing of the predicted mean thermal sensitivity PMV.sup.*. If the air velocity Vair is high, the predicted mean thermal sensitivity PMV.sup.* cannot be accurately obtained.